As a fuser used in an image forming apparatus such as a copying machine or a printer, there is a fuser which uses a fixing belt having small heat capacity as a heat generating part to save energy of an external heat source, and achieves quick rise. In the fixing belt in which both sides thereof are supported by flanges for rotation running, a tensile force can not be applied to an intermediate area of the fixing belt in a rotation axis direction.
Thus, there is a fear that the intermediate area of the fixing belt which is free in a circumferential direction flutters at the time of rotation running. There is a fear that a gap between the fixing belt and the external heat source such as an induced current generating coil (IH coil) varies, and the fixing belt can not achieve uniform heating temperature.